Tantalum pentoxide, also known as "tantalate anhydride", is a white orthorhombic crystal. Its chemical properties are relatively stable, resistant to common acids and alkalis, and can not be attacked by hydrogen chloride or  when heated. Co-melting with alkali metal hydroxide or carbonate can obtain corresponding insoluble tantalate, which is hydrolyzed into hydrated tantalum pentoxide precipitate after washing with water.